1. Field of the Invention
This invention relates to a field effect transistor (FET) with an implant within the gate length of the FET and a method of making the FET.
2. Brief Description of the Prior Art
It has been found that there are advantages for an FET to have an implant in the channel region that does not extend from the source to the drain and is aligned to the gate edge. For example, a pocket implant can be used to reduce short channel length effects. Yet, it can be undesirable to have a pocket implant extend into the source/drain (S/D) area because of resulting increased junction capacitance. It has also been found that there are advantages for an FET to have a region of controlling VT on the source side of the channel with a more conductive VT on the drain side. The short effective channel length and low source resistance of such an FET results in increased drive current and the reduced influence of the drain provides superior short channel characteristics. In the prior art, angled implants and lateral diffusions have been used to obtain channel impurity profiles self-aligned to the gate edge. However, these approaches have disadvantages resulting from restrictions in the channel implant profiles that can be obtained and from the interdependence of the channel profile and the S/D extension profiles. It is therefore apparent that transistors having an independent channel implant region that is self aligned to the S/D edge is highly desirable.